One background art in this technical field is WO2011/040197 (PTL 1). PTL 1 discloses as follows: “In the case where specimen racks are moved in a loop and are repeatedly used in a system in order to prevent an increase in size of a device and complication thereof, a processing speed decreases due to intersection of transport lines, and, in order to prevent such intersection, a complicated mechanism such as an elevator mechanism or a robot hand mechanism has been needed. Empty rack transport lines are disposed at lower positions so as to be independent from a main transport line, an emergency passing line, and a return line, and a rack stocker provided between a storing module and a feeding module is connected to the empty rack transport lines by transport lines inclined in the rack stocker. With this, the intersection of the transport lines is avoided, and therefore empty racks can be continuously supplied and collected. As a result, the intersection of the transport lines can be prevented with a simple configuration without increasing the size of the device or complicating the device, and the empty racks can be continuously supplied and collected without reducing a processing capacity. In addition, it is possible to provide a specimen testing automation system that is highly expandable in accordance with a scale of facilities”.